1. Field of the Invention
The present invention relates generally to a wireless communication device and a wireless communication method for detecting the field intensities of wireless channels.
2. Description of the Related Art
In a recent wireless communication system such as the one defined by IEEE 802.15.4, a predetermined range of radio frequency is divided into wireless channels in such a manner as not to overlap one another in a certain bandwidth. Wireless communications are established between wireless communication devices through a selected one of the divided wireless channels.
In order to select a wireless channel, the wireless communication device verifies communication conditions of all the selectable wireless channels. In the verification process for the communication conditions, field intensity detection (energy scanning) is performed on all the wireless channels. The wireless communication device calculates the interference wave levels and the like of the selectable wireless channels in accordance with the results of detecting the field intensities of the channels, and selects a wireless channel that has a good communication condition.
According to Jpn. Pat. Appln. KOKAI Publication No. 2007-311851, for example, the radio field intensity of an access point is measured at predetermined time intervals. When the radio field intensity falls below the first threshold, energy scanning is conducted at certain scanning intervals to connect to another access point having a better communication condition, or in other words an access point having a higher radio field intensity. When the radio field intensity exceeds the third threshold, the energy scanning is terminated. As taught in this technology, however, if the field intensities of all the wireless channels are detected regularly at certain scan intervals, a period of time of “detection time for one wireless channel” multiplied by “the number of wireless channels” is required. Because the time required for the detection of the field intensity of all the wireless channels cannot be shortened, it is difficult to reduce the processing time for selecting a wireless channel of a good communication condition.
In addition, another problem resides in the technology in which the field intensity detection is performed on all the wireless channels at certain scan intervals; it consumes a large amount of electricity on a regular basis.